In sheep, coat color is influenced by two genes. Gene A influences pigment production, while gene B produces black or brown pigment. If two heterozygous white sheep resulted in 12 white sheep, 3 black sheep, and 1 brown sheep, which genotype(s) of the white sheep explain this data?
A) The white sheep could be A_B_ or aabb.
B) The white sheep must all be A_B_.
C) The white sheep could be A_B_ or A_bb.
D) The white sheep must all be aabb.
E) The white sheep could be A_B_ or aaB_.

Question

Quizplus · Accepted Answer

The white sheep could be A_B_ or A_bb.The white sheep must have at least one recessive allele for both genes. The black sheep must have two dominant alleles for gene B, and the brown sheep must have two recessive alleles for gene B. The only genotype of the white sheep that can explain this data is A_B_ or A_bb.

In Sheep, Coat Color Is Influenced by Two Genes